1. Field of the Invention
This invention relates to the security systems for digital broadcast systems, and in particular to security systems for digital broadcast systems using conditional access modules (CAMs).
2. Description of the Related Art
Illegal reception is a threat which looms over virtually every form of subscription based and pay-per-view transmission system. Broadcast systems are particularly vulnerable because, in a worst case, the illegal interception and decoding may be completely undetectable by the system operator. Therefore, access control is critically important to both the profitability and viability of every such business and system. Access to the transmissions may be controlled through a number of different mechanisms.
A conditional access module or CAM is a known security device that is used to permit or deny access to certain equipment, services or the like. CAMs generally comprise a small processor having one or more electrical contacts. When the CAM is inserted into a CAM reader or other device, the electrical contacts on the CAM and similar contacts in the equipment become intercoupled, allowing the CAM to share information with the device.
CAMs are typically used in integrated receiver/decoders (IRD) for receiving satellite broadcast material. All or part of such broadcast material may be encrypted to limit access to those that have paid the appropriate fee to view the broadcast material. The CAM includes a processor having a memory storing control information that enables decryption of an encrypted television signal for viewing by a user. All broadcast material may be encrypted, thus denying access to all that do not possess the appropriate CAM. Alternatively, only a portion of the broadcast material can be encrypted. This allows those without the appropriate CAM to view some, but not all of the channels. CAMs can also be used to implement pay per view (PPV) services in which the user must pay a fee to receive a specific broadcast at a particular time. Upon receipt of the required fee, the broadcast provider can enable new control signals from the card for access to the other services. Further, in some circumstances, the CAM processors are remotely programmable. That is, program instructions implementing the processor functions can be received by the IRD and loaded into the processor memory, augmenting or substituting for existing processor program instructions.
These conditional access security systems for broadcasters of direct broadcast satellite (DBS) must be inherently dynamic to keep one step ahead of the hacker community. A system which operates using a replaceable CAM is particularly flexible. The CAM is specifically designed to be field replaceable so that the security of the system can be continually evolving. In the event the CAM is “hacked”- and the access control measures have been circumvented, the access control system may be radically updated (beyond what may be accomplished through mere reprogramming of the CAM) by issuing new CAMs to lawful subscribers and new users. New CAMs may also be introduced to increase and improve the functionality and services of the system. However, issuing new CAMs may not prevent illegal reception by those using older CAMS which have been hacked.
When the newer generation of CAM is introduced, it generally is not feasible to immediately recall the older generation of CAM. This means that there would be a period of time when the supply of circumvented, older generation cards is available through the hacker community to utilize in their unlawful attempts to modify systems to receive DBS signals without paying for the services.
This problem is compounded given the lengthy supply lines for manufacturers and retailers to produce and sell DBS systems. This lengthy supply line requires DBS program providers to support older generation CAMs for months and sometimes years after the introduction of the newer generation of CAM. Circumvented CAMs can lead to multi-million dollar losses to the content providers and the DBS broadcaster due to lost revenue from unpaid access to programming.
A less obvious, but equally serious source of losses, is the fact that newer receivers are heavily subsidized by the DBS broadcaster, in the expectation of programming revenue from the new subscriber. In the event that the new receiver is used with a circumvented CAM, these subsidies are not recoverable. Another serious outcome of the use of circumvented CAMs in new receivers, is the reduction in the availability of receivers in the retail supply chain for potential customers. Accordingly, there is a need for system and methods which limit or prevent the use of circumvented CAMs in the newer generation of receivers. It is also recognized that piracy will be discouraged if the newer receivers with advanced features will not operate with older compromised CAMs.